1. Field of the Invention
The present invention is directed to a circuit which can be attached to a telephone line and which can automatically seize a telephone line for an automatic dialing operation.
2. Discussion of the Background
With an increase in crime, the market for home security systems is on the increase. With improvements in wireless security systems, full home alarm systems can be installed by a professional often in less than one hour.
The majority of homes have single telephone line service into the home, which under normal circumstances is more than adequate for phone use. However, when a home owner installs a home security system with a monitoring service which responds to the detection of an alarm situation by automatically dialing a central security monitoring station, then a problem arises. The problem is that if someone in the home is on the phone or the phone was left off-hook, and the security system detects an alarm situation, then the automatic dialer of the security system is not able to dial out since the telephone line is already being used.
One solution for correcting this problem is to simply add a second telephone line to the home. However, such a solution is costly in that an additional telephone line must be installed, and typically the use of the additional telephone line would require a monthly service charge.
Another solution to solving this problem is to add a "line seizure" device in series with the telephone line just before it enters the home. Such a line seizure device will be able to seize the telephone line, i.e., hang up the telephone line, and then redial out to a central security monitoring station. This solution does eliminate the monthly service fees for the operation of the telephone line. However, such conventional line seizure devices which are attached to a telephone line just before it enters the home are expensive and require a dedicated power source. Further, such conventional line seizure devices are hard to install in the average home since the instant the telephone line enters the home the telephone line is split up into a host of parallel lines. The installation of such a conventional line seizure device added to the telephone line just before it enters the home may typically add several hundred dollars to the installation of the home security system.